Project Summary/Abstract. Chronic stress has been shown to critically impact long-term emotional and physical health. In a society where nearly 75% of Americans report stress at levels that exceed what they consider healthy (American Psychological Association, 2015), better understanding of the factors that contribute to effective stress regulation is needed. Stress-physiology coherence is an individual difference measure of the association between subjective experience and peripheral physiological activity under stress, which has recently been shown to be an important correlate of both psychological and physical well-being (Sommerfeldt, Schaefer, Brauer, Ryff, & Davidson, 2019). This proposed project seeks to better understand the neural underpinnings and importance of stress-physiology coherence for stress regulation in aging. Previous work specifically investigated stress-heart rate coherence, the within-individual association between subjective stress and heart rate over the course of a stress-induction paradigm involving computerized cognitive stressor tasks (Sommerfeldt et al., 2019). Over 1,000 participants completed this paradigm as part of the second wave of the Midlife in the United States project (MIDUS; www.midus.wisc.edu). Stress-heart rate coherence was positively associated with psychological well-being, and inversely associated with factors commonly linked to reduced well-being, including anxiety, depression, and levels of pro-inflammatory markers interleukin-6 and C-reactive protein. Furthermore, stress-heart rate coherence was inversely associated with denial coping, suggesting that for at least some individuals, low stress-heart rate coherence may be due to denying one?s own feelings and/or the reality of stressors. Age was also inversely associated with stress-heart rate coherence, such that older participants had a weaker association between their subjective stress and their heart rate. Bodily changes that occur with aging can influence mind-body connections and the experience of affective states (Berry Mendes, 2010). This weakening of the connection between mental and physical states is signified by findings of lower stress-heart rate coherence in older individuals. Using data from additional MIDUS cohorts, the proposed project aims to 1) Establish the functional and structural neural correlates of stress-heart rate coherence, 2) Identify age-related differences in affective biasing and neural correlates of stress-heart rate coherence, and 3) Ascertain longitudinal changes in stress-heart rate coherence and directionality with relation to well-being. This research will facilitate valuable training opportunities in neuroimaging data analysis, writing, public speaking, and mentoring for a doctoral student in Psychology at the University of Wisconsin ? Madison while also establishing the neural correlates of this important individual difference measure, stress-physiology coherence. The project will inform whether stress-physiology coherence is associated with affective biasing of neutral stimuli, particularly in aging, as well as individual differences and potential routes through which stress-physiology coherence may be maintained across the lifespan.